A touch panel is placed over a display device. In view of this, electrode films (sensor electrodes) formed in the display region are transparent oxide conductive films, such as ones of indium tin oxide (ITO) or indium zinc oxide (IZO).
On the other hand, in the picture-frame region, which is outside the display region, metal films with low electric resistance may be used as lines. One problem with metal films is that they may be corroded by impurities, such as water. Thus, impurities such as water may permeate through the surface of the touch panel and corrode the metal films. Such corrosion may reduce the reliability of the lines in the long run.
JP 2011-13725 A describes a capacitive touch panel. This touch panel includes a line protection film provided over the routed lines and a planarizing film provided over the electrodes and routed lines. According to the above document, the line protection film and planarizing film are formed by a printing method using materials such as polysiloxane or an acrylic resin or acrylic monomer. According to the above document, if line protection film and planarizing film are formed using polysiloxane, they will be inorganic insulating films made of silicon oxide; if they are formed using an acrylic resin or acrylic monomer, they will be organic insulating films made of a resin material.